After reading the above posts, I just have to make a couple of comments: I have designed many airplanes in my day, of all sorts and configurations. There are three things that you must do if you want your first flight to be uneventful.

1. You must have enough power to fly the airplane.

2. The C.G.(center of gravity) must be in the exact location for the airfoil being used. In most cases this is between 25 and 30% of the wing chord. I start all my planes out at 27.5% with a full tank of fuel. For bi-planes with straight staggered wings, locate the 27.5 point on each wing, and draw a line between them. Where that line crosses the thrust line is a good starting spot. For wings with sweep back, locating the exact balance point requires additional calculations.

3. You must KNOW your incidence angles. With the stab set at zero, for flat bottom and undercambered wings, I use 1.5 to 2 degrees positive incidence.

DON'T ASSUME ANYTHING. Get an incidence meter and read your incidence angles. Adjust as necessary. Put the plane on a balance stand so you know where you are. I balance so that the stab is at zero with a full tank of fuel. I determine the power requirement from experience.

Don't fly any plane until you KNOW the incidence angles, the correct CG, and are satisfied that the engine will develop enough power to fly the airplane.

Attached are a couple of photos of my new J-3 on it's balance stand. In this case, I had to add 12 oz. to the nose to get it right.